update databases/pgbuildfarm to 4.11

Hello,
Please find attached a patch to update databases/pgbuildfarm to 4.11,
here is the changelog from upstream:
Changes since 4.10:
* Turn down module cleanup verbosity
* Add check for rogue postmasters.
* Add pseudo-branch targets HEAD_PLUS_LATEST and HEAD_PLUS_LATEST2.
* Use Digest::SHA instead of Digest::SHA1.
* Make directory handling more robust in git code.
* Move web transaction into a module procedure.
* Switch to using the porcelain format of git status.
* Provide parameter for core file patterns.
* Use a command file for gdb instead of the -ex option
The web transaction and Digest::SHA changes have allowed the removal of
a couple of long-standing uglinesses on the system. In almost all
cases, the config parameter "aux_path" and the separate
run_web_transaction.pl script are now redundant (the exception is older
Msys systems).
Regards,
--
Nicolas